I've gathered few measurements about couple of heatsinks to this picture. Dynatron data is supplied by manufacturer, and all other data is taken from spcr tests. So if you don't believe what you see, there might be a good reason for that
Dynatron K618 vs. K520 shows dramatic difference between std aluminium HS and heatpipe HS when CFM is extremely slow.
I've build two near silent HTPC:s now, and both of them used aluminium heatsinks with 80mm NF-R8 Noctua fan. I've got Scythe Ninja Mini too, and it was completely useless when I tried to build silent rig. My excel shows why
My first silent htpc setup used intel oem 274g aluminium heatsink for 2.4GHz P4. 80mm Noctua (with U.L.N.A) kept the system way more cooler that with Scythe (same fan, same rpm).
For my current htpc I didn't even thought of putting heatpipe cooler according to my previous experiences. So I put dynatron K520 for i3-2100T (CPU is my only GPU too). Fan is still the same 80mm Noctua with U.L.N.A. Normal htpc use rises CPU temperature typically not more than 5 degrees above case ambient. I've got only one case fan, which is installed inside the PSU. Fan is old Noctua 120mm (don't remember the model) controlled by PSU. Case temperature is typically 10 degrees above ambient temperature. From two meters (sofa) it's impossible to hear my htpc.